Removal of diisopropyl methyl phosphonate (DIMP) from heated metal oxide surfaces

Vasudevan, Ashvin; Senyurt, Elif Irem; Schoenitz, Mirko; Dreizin, Edward L.

doi:10.1016/j.jhazmat.2022.130154

Cited by 5 publications

(9 citation statements)

References 11 publications

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“…The influence of defects and different surface morphology on the decomposition of DIMP has been observed as well. On alumina, the release of 2-propanol is observed; however, on silica, the release of propene was observed instead . To move from model molecules to real toxic nerve agents, it is important to also investigate if the reactivity of sarin with TiO 2 surfaces is similar to that of the simulant DMMP and whether a similar influence of oxide surface defects can take place with sarin decomposition chemistry.…”

Section: Introductionmentioning

confidence: 99%

Decomposition of the Toxic Nerve Agent Sarin on Oxygen Vacancy Sites of Rutile TiO₂(110)

2023

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To design effective personal protective equipment against chemical attacks, the understanding of chemical warfare agents (CWAs) decomposition chemistry is crucial. Metal oxides, particularly TiO 2 have been found to be promising materials to trap and decompose CWAs. This work explores the possible decomposition pathways of sarin on a model rutile TiO 2 (110) surface with and without the presence of surface oxygen vacancies. Sarin adsorbs on the surface mainly by its P�O unit via a dative P�O-Ti 5c bond, similar to its simulant dimethyl methylphosphonate (DMMP). Sarin decomposition on the pristine surface is possible at 455 K and proceeds via O−C bond cleavage, with a barrier of 1.17 eV, resulting in the production of surface-bonded monofluorophosphate and isopropoxy, while P−OR (R = C 3 H 7 isopropyl) or P−F cleavage is highly activated with barriers larger than 2 eV. However, the production of gas-phase propene after O−C cleavage has a high activation barrier (1.6 eV). In the presence of O vacancies, the barriers to cleave the P−F and P−OR bonds are greatly reduced and these cleavages become possible at a moderate temperature (425 K). In comparison to its simulant DMMP, the decomposition of sarin proceeds faster on the oxygen vacancy as the cleavage of the P−F bond is more facile and the binding of F on surface Ti creates a thermodynamically stable intermediate. The electronic effects of the F ligand also facilitate the P−OR bond cleavage at the O vacancy site. Frequency calculations validate the energy pathways: intact molecular adsorption of sarin can explain the experimental spectrum at room temperature, while further decomposition by C−O or P−F bond cleavage, presumably on the pristine surface and at O vacancies, respectively, is responsible for the spectral evolution seen at 500 K, in agreement with calculated barriers.

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Section: Introductionmentioning

confidence: 99%

Decomposition of the Toxic Nerve Agent Sarin on Oxygen Vacancy Sites of Rutile TiO₂(110)

2023

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“…Specifically, the P�O mode red shifts relative to the gas-phase frequency when bound to metal-oxide surfaces. 4,29 It is also important to note that the concentration of DIMP may hinder further binding due to steric hindrance caused by its bulky nature, preventing access to active sites on the metal-oxide surface. Figure 4 depicts snapshots of a few representative molecular dynamics trajectories for the decomposition of DIMP on the alumina (110) surface.…”

Section: Dimp Adsorptionmentioning

confidence: 99%

“…3 Thermal decomposition on γ-Al 2 O 3 resulted in the release of 2-propanol and propene, suggesting diverse reaction pathways at different temperatures. 29…”

Section: Comparing Dimp Vs Sarinmentioning

confidence: 99%

Diisopropyl Methylphosphonate and Sarin Decomposition on Pristine vs Hydroxylated Alumina Surfaces: Mechanistic Predictions from Ab Initio Molecular Dynamics

Biswas,

Wong

2024

J. Phys. Chem. C

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Understanding the reactivity of chemical warfare agents on material surfaces is essential for mitigating and controlling their chemical/biological activity. Using ab initio molecular dynamics, we compare the adsorption and decomposition of sarin and its simulant, diisopropyl methylphosphonate (DIMP), on both pristine and hydroxylated alumina surfaces at various temperatures. Our extensive calculations confirm that DIMP is a suitable simulant for sarin experimental studies on pristine alumina surfaces due to their similar adsorption configurations and reaction dynamics. Moreover, our ab initio molecular dynamics simulations predict C−O bond cleavage to be the initial decomposition step for both DIMP and sarin on the pristine surface. We also identify an additional potential decomposition route for sarin via cleavage of the P−F bond. While similarities exist on the pristine surface, differences between sarin and DIMP emerge on the hydroxylated surface at elevated temperatures. This work provides detailed insights into these atomistic decomposition mechanisms and highlights the utility of predictive quantum dynamics simulations for evaluating the suitability of simulants to guide future experimental investigations of these hazardous compounds.

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“…However, due to the inherent complexity of these high-temperature experiments, a detailed understanding of the PFAS degradation mechanisms on these material surfaces is scarce and still in its infancy. , In this work, we present the first ab initio molecular dynamics (AIMD) study for investigating a wide range of temperature-dependent degradation dynamics of perfluorooctanoic acid (PFOA) on various surfaces of γ-Al 2 O 3 . We have chosen to investigate γ-Al 2 O 3 since previous work by us and our experimental collaborators , has shown that γ-Al 2 O 3 has a high degree of surface heterogeneity with Al atoms exhibiting tri-, tetra-, and pentacoordination motifs (depending on the crystallographic plane), which can enhance reactivity. To probe the degradation dynamics of PFOA at a predictive quantum mechanical level, we carried out large-scale AIMD calculations on the (100) and (110) surfaces of γ-Al 2 O 3 (taking into account possible surface defects) over a wide range of temperatures.…”

Section: Introductionmentioning

confidence: 99%

Degradation of Perfluorooctanoic Acid on Aluminum Oxide Surfaces: New Mechanisms from Ab Initio Molecular Dynamics Simulations

Biswas

Wong

2023

Environ. Sci. Technol.

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Perfluorooctanoic acid (PFOA) is a part of a large group of anthropogenic, persistent, and bioaccumulative contaminants known as per-and polyfluoroalkyl substances (PFAS) that can be harmful to human health. In this work, we present the first ab initio molecular dynamics (AIMD) study of temperaturedependent degradation dynamics of PFOA on ( 100) and ( 110) surfaces of γ-Al 2 O 3 . Our results show that PFOA degradation does not occur on the pristine (100) surface, even when carried out at high temperatures. However, introducing an oxygen vacancy on the (100) surface facilitates an ultrafast (<100 fs) defluorination of C−F bonds in PFOA. We also examined degradation dynamics on the (110) surface and found that PFOA interacts strongly with Al(III) centers on the surface of γ-Al 2 O 3 , resulting in a stepwise breaking of C−F, C−C, and C−COO bonds. Most importantly, at the end of the degradation process, strong Al−F bonds are formed on the mineralized γ-Al 2 O 3 surface, which prevents further dissociation of fluorine into the surrounding environment. Taken together, our AIMD simulations provide critical reaction mechanisms at a quantum level of detail and highlight the importance of temperature effects, defects, and surface facets for PFOA degradation on reactive surfaces, which have not been systematically explored or analyzed.

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Removal of diisopropyl methyl phosphonate (DIMP) from heated metal oxide surfaces

Cited by 5 publications

References 11 publications

Decomposition of the Toxic Nerve Agent Sarin on Oxygen Vacancy Sites of Rutile TiO₂(110)

Decomposition of the Toxic Nerve Agent Sarin on Oxygen Vacancy Sites of Rutile TiO₂(110)

Diisopropyl Methylphosphonate and Sarin Decomposition on Pristine vs Hydroxylated Alumina Surfaces: Mechanistic Predictions from Ab Initio Molecular Dynamics

Degradation of Perfluorooctanoic Acid on Aluminum Oxide Surfaces: New Mechanisms from Ab Initio Molecular Dynamics Simulations

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Removal of diisopropyl methyl phosphonate (DIMP) from heated metal oxide surfaces

Cited by 5 publications

References 11 publications

Decomposition of the Toxic Nerve Agent Sarin on Oxygen Vacancy Sites of Rutile TiO2(110)

Decomposition of the Toxic Nerve Agent Sarin on Oxygen Vacancy Sites of Rutile TiO2(110)

Diisopropyl Methylphosphonate and Sarin Decomposition on Pristine vs Hydroxylated Alumina Surfaces: Mechanistic Predictions from Ab Initio Molecular Dynamics

Degradation of Perfluorooctanoic Acid on Aluminum Oxide Surfaces: New Mechanisms from Ab Initio Molecular Dynamics Simulations

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Decomposition of the Toxic Nerve Agent Sarin on Oxygen Vacancy Sites of Rutile TiO₂(110)

Decomposition of the Toxic Nerve Agent Sarin on Oxygen Vacancy Sites of Rutile TiO₂(110)